<template>
    <el-color-picker v-model="theme"
        :predefine="['#4458FE', '#1890ff', '#304156','#212121','#11a983', '#13c2c2', '#6959CD', '#f5222d', ]"
        class="theme-picker" popper-class="theme-picker-dropdown" />
</template>

<script>
    import Cookies from 'js-cookie';
    const version = require('element-ui/package.json').version // element-ui version from node_modules
    const ORIGINAL_THEME = '#409EFF' // default color

    export default {
        props: {
            default: {
                // 初始化主题，可由外部传入
                type: String,
                // default: '#EB815B'
                default: "" + Cookies.get('MY_SET') + "",
            }
        },
        data() {
            return {
                chalk: '', // content of theme-chalk css
                theme: ORIGINAL_THEME
            }
        },
        mounted() {
            if (this.default != "undefined") {
                this.theme = JSON.parse(this.default).value;
            }
            this.$emit("change", this.theme);
        },
        watch: {
            theme(val, oldVal) {
                if (typeof val !== "string") {
                    val = "#409EFF";
                    this.theme = val;
                    // 响应父组件 存入cookie-vuex
                    this.$emit("change", this.theme);
                } else {
                    const themeCluster = this.getThemeCluster(val.replace("#", ""));
                    /* 解决replace报错 */
                    if (!oldVal) {
                        oldVal = "#409EFF";
                    }
                    const originalCluster = this.getThemeCluster(oldVal.replace("#", ""));
                    const getHandler = (variable, id) => {
                        return () => {
                            const originalCluster = this.getThemeCluster(
                                ORIGINAL_THEME.replace("#", "")
                            );
                            const newStyle = this.updateStyle(
                                this[variable],
                                originalCluster,
                                themeCluster
                            );

                            let styleTag = document.getElementById(id);
                            if (!styleTag) {
                                styleTag = document.createElement("style");
                                styleTag.setAttribute("id", id);
                                document.head.appendChild(styleTag);
                            }
                            styleTag.innerText = newStyle;
                        };
                    };
                    const chalkHandler = getHandler("chalk", "chalk-style");
                    if (!this.chalk) {
                        const url = `https://unpkg.com/element-ui@${version}/lib/theme-chalk/index.css`;
                        this.getCSSString(url, chalkHandler, "chalk");
                    } else {
                        chalkHandler();
                    }
                    const styles = [].slice
                        .call(document.querySelectorAll("style"))
                        .filter((style) => {
                            const text = style.innerText;
                            return (
                                new RegExp(oldVal, "i").test(text) &&
                                !/Chalk Variables/.test(text)
                            );
                        });
                    styles.forEach((style) => {
                        const {
                            innerText
                        } = style;
                        if (typeof innerText !== "string") return;
                        style.innerText = this.updateStyle(
                            innerText,
                            originalCluster,
                            themeCluster
                        );
                    });
                    /* 存储 */
                    this.$emit("change", this.theme);
                }
            }
        },

        methods: {
            updateStyle(style, oldCluster, newCluster) {
                let newStyle = style;
                oldCluster.forEach((color, index) => {
                    newStyle = newStyle.replace(new RegExp(color, "ig"), newCluster[index]);
                });
                return newStyle;
            },

            getCSSString(url, callback, variable) {
                const xhr = new XMLHttpRequest();
                xhr.onreadystatechange = () => {
                    if (xhr.readyState === 4 && xhr.status === 200) {
                        this[variable] = xhr.responseText.replace(/@font-face{[^}]+}/, "");
                        callback();
                    }
                };
                xhr.open("GET", url);
                xhr.send();
            },

            getThemeCluster(theme) {
                const tintColor = (color, tint) => {
                    let red = parseInt(color.slice(0, 2), 16);
                    let green = parseInt(color.slice(2, 4), 16);
                    let blue = parseInt(color.slice(4, 6), 16);

                    if (tint === 0) {
                        // when primary color is in its rgb space
                        return [red, green, blue].join(",");
                    } else {
                        red += Math.round(tint * (255 - red));
                        green += Math.round(tint * (255 - green));
                        blue += Math.round(tint * (255 - blue));

                        red = red.toString(16);
                        green = green.toString(16);
                        blue = blue.toString(16);

                        return `#${red}${green}${blue}`;
                    }
                };

                const shadeColor = (color, shade) => {
                    let red = parseInt(color.slice(0, 2), 16);
                    let green = parseInt(color.slice(2, 4), 16);
                    let blue = parseInt(color.slice(4, 6), 16);

                    red = Math.round((1 - shade) * red);
                    green = Math.round((1 - shade) * green);
                    blue = Math.round((1 - shade) * blue);

                    red = red.toString(16);
                    green = green.toString(16);
                    blue = blue.toString(16);

                    return `#${red}${green}${blue}`;
                };

                const clusters = [theme];
                for (let i = 0; i <= 9; i++) {
                    clusters.push(tintColor(theme, Number((i / 10).toFixed(2))));
                }
                clusters.push(shadeColor(theme, 0.1));
                return clusters;
            },
        }
    }
</script>

<style>
    .theme-message,
    .theme-picker-dropdown {
        z-index: 99999 !important;
    }

    .theme-picker .el-color-picker__trigger {
        height: 26px !important;
        width: 26px !important;
        padding: 2px;
    }

    .theme-picker-dropdown .el-color-dropdown__link-btn {
        display: none;
    }
</style>
